4850 x2 will not max crysis without AA. I have one so I know for sure. COD6 is not intensive at all, so you are good there.
You will need a 5850 or better to get 30fps in crysis. (though it still may dip occasionally)
Cards include: 5850, 4870 x2, 5870, GTX 295, 5970.
Thats it for single card solutions...
You dont need to max it though...